共查询到20条相似文献,搜索用时 93 毫秒
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自"十三五"规划提出以来,国家对生态环境保护工作给予了高度重视,这给环境检测工作带来了巨大的机遇和挑战[1].实验室样品管理是环境检测工作的重要组成环节,也是实验室管理、实验室认可、计量认证的重要内容,更是检测结果公正性、科学性和准确性的重要保障[2].传统实验室在进行接样、暂存、流转、留样等样品管理全流程工作中需要大... 相似文献
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胶束电动毛细管色谱双通道电化学检测尼群地平 总被引:3,自引:0,他引:3
创建了尼群地平的胶束电动毛细管色谱双通道电化学检测的分析新方法。采用 两台安培检测器并联构成双通道检测系统,采用单一碳糊工作电极,两台安培检测 器的检测电位分别设为+0.7V和-0.8V(vs.SCE)同,同时对尼群地平进行氧化和还原 测定,并实时对数据进行采集、处理,以图形方式显示。采用NH3-NH4Cl为背景电 解质,并加入十二烷基硫酸钠(SDS)和甲醇组成运行电泳介质,应用氧化、还原 双通道检测系统对尼群地平及其片剂进行了胶束电动毛细管色谱分离检测;对工作 电极的选择、电极电位的选择、SDS的浓度、甲醇浓度、运行缓冲溶液种类以及工 作电压和进样时间对分离检测的影响进行了研讨,取得满意结果。 相似文献
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推导了高效毛细管电泳碳柱电极安培电化学检测的检测电流表达式,并以自制毛细管电泳/电化学检测系统对其进行了实验验证。对给定直径的工作电极,检测电流正比于碳柱工作电极插入检测毛细管长度的2/3次方,也正比于液体电渗平均体积流速的1/3次方。实验结果与公式吻合很好,说明了检测电流表达式的正确性。 相似文献
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一种基于双工作电极-双通道的毛细管电泳电化学检测系统 总被引:2,自引:0,他引:2
报道了一种双工作电极-双通道毛细管电泳电化学检测系统,实现电导和安培 同时检测或者安培与安培检测联用,使两种方法相互补充,发挥各自的优势。其中 ,工作电极与检测池的制作工艺简单,操作简便,通过不锈钢针管和毛细管作为套 管,无需三维微调装置即可简单实现双工作电极的准确放置及分离毛细管与工作电 极的准确对接,并根据分析体系的需要采用不同类型的工作电极和检测器;同时采 用复式滤波电路解决了不同检测器之间的电场叠加对输出信号的干扰问题。采用该 装置可以同时检测复杂体系中的电活性和惰性物质,或同时测定只能氧化或只能还 原的物质,还可以对具有氧化还原性质的物质进行纯度的确证。将该装置应用于实 际样品的测定,节约了分析时间,提高了分析速度,扩大了检测范围,结果令人满 意。 相似文献
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采用硼掺杂金刚石(Boron-doped diamond,BDD)薄膜电极为工作电极,利用流动注射分析方法测定水体化学需氧量(COD),根据水样中有机物组分在工作电极表面氧化消耗的电量(Qoxidation)测定样品的COD值。考察了一些基本参数包括载液、工作电位、流速对检测信号的影响并选定了最佳检测条件。在最佳检测条件下,本法检测COD的线性范围为2.5~120 mg/L,检出限为1 mg/L。用该法测定化工厂和食品厂废水的COD值,相对标准偏差和回收率分别在2.4%~4.8%和96%~106%之间,且检测结果与国家标准方法(CODcr法)有良好的一致性。 相似文献
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Multiconformation continuum electrostatics (MCCE) explores different conformational degrees of freedom in Monte Carlo calculations of protein residue and ligand pKas. Explicit changes in side chain conformations throughout a titration create a position dependent, heterogeneous dielectric response giving a more accurate picture of coupled ionization and position changes. The MCCE2 methods for choosing a group of input heavy atom and proton positions are described. The pKas calculated with different isosteric conformers, heavy atom rotamers and proton positions, with different degrees of optimization are tested against a curated group of 305 experimental pKas in 33 proteins. QUICK calculations, with rotation around Asn and Gln termini, sampling His tautomers and torsion minimum hydroxyls yield an RMSD of 1.34 with 84% of the errors being <1.5 pH units. FULL calculations adding heavy atom rotamers and side chain optimization yield an RMSD of 0.90 with 90% of the errors <1.5 pH unit. Good results are also found for pKas in the membrane protein bacteriorhodopsin. The inclusion of extra side chain positions distorts the dielectric boundary and also biases the calculated pKas by creating more neutral than ionized conformers. Methods for correcting these errors are introduced. Calculations are compared with multiple X‐ray and NMR derived structures in 36 soluble proteins. Calculations with X‐ray structures give significantly better pKas. Results with the default protein dielectric constant of 4 are as good as those using a value of 8. The MCCE2 program can be downloaded from http://www.sci.ccny.cuny.edu/~mcce . © 2009 Wiley Periodicals, Inc. J Comput Chem, 2009 相似文献
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Kellen Heloizy Garcia Freitas 《Talanta》2010,81(3):1102-12
A simple electrochemical method was developed for the single and simultaneous determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in food samples using square-wave voltammetry (SWV). A carbon composite electrode modified (MCCE) with copper (II) phosphate immobilized in a polyester resin was proposed. The modified electrode allowed the detection of BHA and BHT at potentials lower than those observed at unmodified electrodes. A separation of about 430 mV between the peak oxidation potentials of BHA and BHT in binary mixtures was obtained. The calibration curves for the simultaneous determination of BHA and BHT demonstrated an excellent linear response in the range from 3.4 × 10−7 to 4.1 × 10−5 mol L−1 for both compounds. The detection limits for the simultaneous determination of BHA and BHT were 7.2 × 10−8 and 9.3 × 10−8 mol L−1, respectively. In addition, the stability and repeatability of the electrode were determined. The proposed method was successfully applied in the simultaneous determination of BHA and BHT in several food samples, and the results obtained were found to be similar to those obtained using the high performance liquid chromatography method with agreement at 95% confidence level. 相似文献
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Nyholm L 《The Analyst》2005,130(5):599-605
During the last few years there has been a rapid increase in the use of electrochemical reactions in lab-on-a-chip devices. This development, which has so far mainly focussed on electrochemical detection in chip-based capillary electrophoresis, can be explained by the fact that electrochemical techniques and devices are particularly well-suited for inclusion in lab-on-a-chip systems. The most important reason for this is that the required electrodes can readily be manufactured and miniaturised without loss of analytical performance using conventional microfabrication methods. In this Research Highlight article, the developments during the last three years concerning electrochemical techniques for lab on-a-chip applications are discussed, with particular focus on emerging electrochemical methods for sample clean-up and preconcentration, electrochemical derivatisation and electrochemical detection in chip-based capillary electrophoresis. 相似文献
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Carbon nanotubes (CNTs) have been incorporated in electrochemical sensors to decrease overpotential and improve sensitivity. In this review, we focus on recent literature that describes how CNT-based electrochemical sensors are being developed to detect neurotransmitters, proteins, small molecules such as glucose, and DNA. Different types of electrochemical methods are used in these sensors including direct electrochemical detection with amperometry or voltammetry, indirect detection of an oxidation product using enzyme sensors, and detection of conductivity changes using CNT-field effect transistors (FETs). Future challenges for the field include miniaturizing sensors, developing methods to use only a specific nanotube allotrope, and simplifying manufacturing. 相似文献
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《Analytical letters》2012,45(1-3):258-270
The design and fabrication of a home-made thin-layer electrochemical flow cell are reported. The performance and electrochemical characteristics of thin-layer cells are evaluated in terms of flow rate and channel thickness. The adaptability of the flow cell for amperometric and electrochemiluminescence measurements is demonstrated. Also, a flow injection method comprising electrochemical generation followed by spectrophotometric detection is proposed for determination of bromide using the fabricated cell. The influence of chemical, electrochemical, and flow parameters on the absorbance and current signals are investigated, and under optimized conditions, the analytical features of the proposed method with respect to bromide detection are evaluated. 相似文献
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Marek Trojanowicz 《Analytica chimica acta》2009,653(1):36-58
Recent years have provided numerous new examples of applying flow-through electrochemical detectors in chemical analysis. This review, based on about 250 original research papers cited from the current analytical literature, presents their application in flow analysis and capillary electrophoretic methods. Example applications are also given for arrays of electrochemical sensors in flow analysis and electrochemical detection in microfluidic systems. Potentiometric detection with ion-selective electrodes predominates in flow analysis carried out mostly in a flow-injection system, while amperometric and conductivity detections are most commonly employed in capillary electrophoresis. 相似文献
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Determination of inorganic phosphate is of very high importance in environmental and health care applications. Hence knowledge of suitable analytical techniques available for phosphate sensing for different applications becomes essential. Electrochemical methods for determining inorganic phosphate have several advantages over other common techniques, including detection selectivity, stability and relative environmental insensitivity of electroactive labels. The different electrochemical sensing strategies adopted for the determination of phosphate using selective ionophores are discussed in this review. The various sensing strategies are classified based on the electrochemical detection techniques used viz., potentiometry, voltammetry, amperometry, unconventional electrochemical methods etc., The enzymatic sensing of phosphate coupled with electrochemical detection is also included. Various electroanalytical methods available in the literature are assessed for their merits in terms of selectivity, simplicity, miniaturisation, adaptability and suitability for field measurements. 相似文献
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电化学免疫分析法研究进展 总被引:27,自引:8,他引:27
电化学免疫分析法是将免疫分析与电化学分析技术相结合的一种免疫分析新方法,近十多年来,电化免疫分析的研究有了迅速的发展。本文对电化学的免疫分析法的标记物、免疫方法、电化学检测技术进行了概括总结,并展望了电化学免疫分析的发展前景。 相似文献